Heather Reich has been studying bears in Montana for a decade, but she wanted to try an experiment.

The 39-year-old wildlife biologist worked with her photographer husband, Derek, to tie up a dead deer to an electric fence. The couple was trying to use “aversive conditioning” on bears to get them to stay away from areas with lots of people.

The bear spent an incredible 14 hours trying to get its jaws on the electrified deer.Barcroft

Barcroft“These bears needed to be taught to avoid these areas for their own good,” the 55-year-old photographer told Barcroft Media.

But this persistent grizzly spent 14 hours destroying the fence, and eventually dragged the deer back into the woods for supper.

“This footage shows us how tenacious bears can be,” Reich said of the video that shows the bear’s feat.

“You would think after being shocked, a bear would just leave the area, not that it would spend 14 hours working out how to disarm the setup,” she added. “He spent a lot of time just staring at the deer, trying to figure out how to get it without getting shocked.”

The big bear “outsmarted the trap” by disconnecting the car battery from the charger and quickly stealing the carcass, according to Barcroft.

The pair filmed the experiment back in 2007, but only recently released the video.

“This footage is unique in that no human was present, so the behavior is as genuine as it gets with these animals,” Derek said.